Title

Battery Efficiency
Problem Scenario
I always need batteries to power things around the house, they become fairly expensive after a while. I want to know which type of battery has the most charge for the money.
Broad Question
What battery type is the most efficient?

Specific Question

Which type of battery lasts the longest for the amount it costs?

Hypothesis

I am hypothesizing that the [[#|lithium batteries]] will last the longest, but the rechargeable batteries will be the most cost efficient.
Graph of Hypothesis


Variables

Independent Variable:

Type of battery

Dependent Variable:

Length and power of charge

Variables That Need To Be Controlled:

Same battery size, same power usage

Vocabulary List That Needs Explanation

NiMH: Nickel-Metal hydride, this is the most common type of rechargeable batteries.

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Lithium: A very highly reactive solid that is only found in compounds, it is also the least dense solid element.

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Alkaline: A reaction of zinc and manganese dioxide, it gets its name because it has an alkaline electrolyte.

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Battery: A device that has many electrochemical cells, these cells hold power in the form of chemical energy. Batteries convert the chemical energy to electrical energy and output it so it can be used by the consumer.

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mAh: Milliampere-hour this is a unit of measure for electricity. It is used to determine how much power a battery can hold at one time.

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General Plan

I am going to put two batteries in a flashlight and put a light sensor against the bulb. I will record the length and power of the charge to determine which battery lasts the longest. I will then find out how much each battery costs to determine the length of time (in hours) for a certain cost.

Potential Problems And Solutions

The bulb of the flashlight could run out, to prevent this I am using 2 identical [[#|LED flashlights]].

Safety Or Environmental Concerns

The materials from the old batteries could pollute the landfill they are buried in. I will make sure that they are recycled appropriately.

Experimental Design

Number Of Comparison Categories:

I will be comparing 4 different types of batteries.

Number of Comparison Samples:

I will be testing each type of battery twice.

Number Of Observations In Each Sample:

For each comparison category I will be measuring the amount of time the battery lasts, as well as the cost of each battery.

When data will be collected

February 1 - February 28

Where will data be collected?:

The data will be collected under a table with blankets hanging over it, so no additional light can get in.

Resources and Budget Table

Item	Number needed	Where I will get this	Cost
AA Alkaline	4	Amazon	$2.37
AA Lithium	4	Amazon	$8.14
AA Rechargeable 1300mAh	4	Amazon	$13.89
AA Rechargeable 2300mAh	4	Amazon	$10.49

Detailed Procedure

1. Put a battery in a flashlight
2. Start recording the light with a light sensor
3. Turn on the light
4. Once the battery dies save the results
5. Take the battery out
6. Repeat step 1 with a different battery

Diagram

Photo List

Time Line

Feb 1: Timeline and Procedure done March 1: Analysis [[#|[[#|complete]]]] March 15: Wiki Complete March 29: KMS science fair

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Feb 4: All experiments should be started March 15: Discussion/Backround/Ex. done March 22: Poster complete

Data Table

Battery Type	Hours
Alkaline	89.83
Lithium	14.82
Recharge 1300 mAh	10.01
Recharge 2300 mAh	11.995

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Data Analysis

All Raw Data

Alkaline 86.75 Hours
Alkaline 2 92.91 Hours

Lithium 15.24 Hours
Lithium 2 14.40 Hours

Recharge 1300mh 9.34 Hours
Recharge 1300mh 2 10.68 Hours

Recharge 2300mh 10.83 Hours
Recharge 2300mh 2 13.16 Hours

Graphs

Photos

Results

I got many suspected and unsuspected results. I hypothesized that the alkaline batteries would last the least amount of time, but the opposite happened. They lasted the longest, but they weren't bright for very long. They were at max brightness for the shortest time, but they then died off to a low light level and stayed that way for many days; but the usable power is very low. The same thing happened for the rechargeable batteries, but not quite as long. The [[#|lithium batteries]] had 14 hours of usable power, and died right off; there was no long streaks of low power level. In general, the alkaline batteries lasted the longest. If people want a battery that has the most usable charge, lithium wins because it had the most usable power.

Conclusion

I have concluded that the 2300mAh rechargeable batteries are the most efficient because they have the second longest amount of usable power. They cost a bit more than the lithium batteries, but they can also be recharged. This means that they have multiple uses, but they can't last as long on one charge.

Discussion

I already knew how batteries worked, so this helped me have a better understanding of the experiment. I hypothesized that the alkaline batteries would last the shortest length of time, the rechargeable batteries would last 4 times as long, and the lithium batteries would last 9 times as long as the alkaline batteries. My data somewhat supported my hypothesis because I expected the alkaline batteries to last the least, and the lithium the most, with the rechargeable batteries somewhere in between. The alkaline batteries lasted the longest even though they didn't have very much usable power. If people were to buy a set of batteries, I would recommend that they buy a pair of rechargeable batteries because they can be reused. They may cost a bit more initially, but over time they are very cost effective.

Benefit to Community and/or Science

People always spend a lot of money on batteries and it becomes expensive. The general public needs to know which battery type has the longest lasting charge for the money. This will help them because they will know what type of battery to get if they want to spend the least amount of money.

Background Research

A normal alkaline AA battery lasts about 8 hours in a normal flashlight. A lithium battery is supposed to last 9 times longer than an alkaline battery, meaning that it should last around 72 hours.
An alkaline battery works because of the reaction between zinc and manganese dioxide, they are 80% of the manufactured batteries in the United States.
Lithium has the Atomic number of 3 and is the least dense solid element on the periodic table. It outputs 3.7 V instead of the normal 1.5 V from an Alkaline battery.
Nickel-metal hydride batteries are the most common type of rechargeable batteries. They have a voltage of 1.2 V per cell. They also have a very high discharge rate, about 20% of charge is lost on the first day, only 4% is lost the remaining days of its charge.

References

"Molecular Expressions: Electricity and Magnetism: Alkaline Battery." Molecular Expressions: Electricity and Magnetism: Alkaline Battery. N.p., n.d. Web. 19 Mar. 2013.

The batteries themselves

"How Do Rechargeable (that Is, Zinc-alkaline or Nickel-cadmium) Batteries Work And What Makes the Reactions Reversible in Some Batteries, but Not in Others? : Scientific American." How Do Rechargeable (that Is, Zinc-alkaline or Nickel-cadmium) Batteries Work And What Makes the Reactions Reversible in Some Batteries, but Not in Others? : Scientific American. N.p., n.d. Web. 19 Mar. 2013.

Abstract

I need to buy batteries a lot so I decided to find out which battery type is the most efficient. I found out that 2300mAh rechargeable batteries are the most efficient battery type I tested. I did this by putting a flashlight in front of a light level sensor and found out how long the light shone before it died. I found that the alkaline battery lasted the longest, but the light level was very low. The lithium battery had the most amount of usable power, and the rechargeable batteries were right behind that. Due to the fact that the 2300mAh battery lasted almost as long as the lithium battery, but can be recharged to be used multiple times; it is a more cost effective battery.